It was not until the supreme lending crisis(次贷危机)had caused great damage to the American financial system ________ Americans realized the severity(严重性)of the situation．

A．which

B．that

C．what

D．when

There happened earthquakes in many places recently, one of ________ in Japan．

A．the others

B．them

C．it

D．which

The goals of this project are to promote the commercialization of home-use robots, whose market is smaller than ________ for industrial robots, and to develop safety technologies and standards．

A．it

B．them

C．that

D．one

Scientists say human activity contributes to climate change, but they do not agree on the rate ________ climate change may be developing．

A．with which

B．with that

C．at which

D．at that

In the meeting, the president indicated that Tom would ________ the management of the finance department from July 1^st．

A．take in

B．take up

C．take off

D．take down

The school recommends parents ________ their children to swim in rivers or lakes during summer holidays．

A．not permit

B．do not permit

C．mustn't permit

D．couldn't permit

Although we haven't got accurate statistics, it is estimated that ________ 300 factories in this province closed down during the economic crisis．

A．finally

B．previously

C．obviously

D．approximately

Everyone dose something for ________ purpose; there is no such ________ person who dose things for nothing in the world．

A．a; a

B．a;/

C．the; a

D．the;/

I ________ hardly remember any occasion ________ I get caught in a traffic jam in our town．

A．should; when

B．can; where

C．may; where

D．can; when

Don't forget to return your room key to the front desk when you ________ of the hotel．

A．turn out

B．check out

C．hang out

D．drop out